Normal NAS file servers export file abstractions via protocols such as NFS and Microsoft's CIFS. SAN protocols, such as Sun's original ND protocol, and various SCSI transport protocols, operate at the disk block level, rather than the file level. There are a number of management operations that can be done at the file level, and that are also useful to have at the block level. These include the ability to make point-in-time copies of a partition, to relocate the contents of a partition efficiently from one physical location to another, and the ability to replicate point-in-time copies of a partition to multiple locations.